Abstract: Bed separation will cause anchor to generate additional stress, when the deformation of surrounding rock of roadway is uncoordinated. Based on the existing elastic analysis, an elastoplastic mechanical model of the bolt additional stress caused by the further expansion of the bed separation is established. According to the bolt pulling load to the bolt function mechanism during the relative movement of the strata, through the selection of two-stage linear function shear slide model, the sliding range in both left and right sides of the bed separation is determined; and the stress distribution mode of the anchored mass under the bed separation effect is obtained. Loading process of the anchored mass under the bed separation function is general divided into four stages, i.e. elastic stage, one side into elastoplastic stage, both left and right sides into elastoplastic stage and another side sliding larger with one side sliding all. By means of the parameters analysis of different separation values and different separation locations, the analysis finds that under the condition of the same bed separation location, the larger bed separation value, the larger the additional stress occurred from the bolt by the bed separation would be. Under the condition of the same bed separation value, elastoplastic stage basic trend and elastic stage trend are same, which presents as the stress at the center of the bolt would be minimum; the additional stress occurred close to the boundary bed separation would be larger.

Key words: bed separation, bed separation value, bed separation location, anchored mass loading, shear slide model, sliding range, elastoplastic analysis